1.\" Copyright (c) 2003-2009 Tim Kientzle 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd April 3, 2017 28.Dt ARCHIVE_READ_DISK 3 29.Os 30.Sh NAME 31.Nm archive_read_disk_new , 32.Nm archive_read_disk_open , 33.Nm archive_read_disk_open_w , 34.Nm archive_read_disk_set_behavior , 35.Nm archive_read_disk_set_symlink_logical , 36.Nm archive_read_disk_set_symlink_physical , 37.Nm archive_read_disk_set_symlink_hybrid , 38.Nm archive_read_disk_entry_from_file , 39.Nm archive_read_disk_gname , 40.Nm archive_read_disk_uname , 41.Nm archive_read_disk_set_uname_lookup , 42.Nm archive_read_disk_set_gname_lookup , 43.Nm archive_read_disk_set_standard_lookup , 44.Nm archive_read_disk_descend , 45.Nm archive_read_disk_can_descend , 46.Nm archive_read_disk_current_filesystem , 47.Nm archive_read_disk_current_filesystem_is_synthetic , 48.Nm archive_read_disk_current_filesystem_is_remote , 49.Nm archive_read_disk_set_matching , 50.Nm archive_read_disk_set_metadata_filter_callback , 51.Nd functions for reading objects from disk 52.Sh LIBRARY 53Streaming Archive Library (libarchive, -larchive) 54.Sh SYNOPSIS 55.In archive.h 56.Ft struct archive * 57.Fn archive_read_disk_new "void" 58.Ft int 59.Fn archive_read_disk_open "struct archive *" "const char *" 60.Ft int 61.Fn archive_read_disk_open_w "struct archive *" "const wchar_t *" 62.Ft int 63.Fn archive_read_disk_set_behavior "struct archive *" "int" 64.Ft int 65.Fn archive_read_disk_set_symlink_logical "struct archive *" 66.Ft int 67.Fn archive_read_disk_set_symlink_physical "struct archive *" 68.Ft int 69.Fn archive_read_disk_set_symlink_hybrid "struct archive *" 70.Ft const char * 71.Fn archive_read_disk_gname "struct archive *" "gid_t" 72.Ft const char * 73.Fn archive_read_disk_uname "struct archive *" "uid_t" 74.Ft int 75.Fo archive_read_disk_set_gname_lookup 76.Fa "struct archive *" 77.Fa "void *" 78.Fa "const char *(*lookup)(void *, gid_t)" 79.Fa "void (*cleanup)(void *)" 80.Fc 81.Ft int 82.Fo archive_read_disk_set_uname_lookup 83.Fa "struct archive *" 84.Fa "void *" 85.Fa "const char *(*lookup)(void *, uid_t)" 86.Fa "void (*cleanup)(void *)" 87.Fc 88.Ft int 89.Fn archive_read_disk_set_standard_lookup "struct archive *" 90.Ft int 91.Fo archive_read_disk_entry_from_file 92.Fa "struct archive *" 93.Fa "struct archive_entry *" 94.Fa "int fd" 95.Fa "const struct stat *" 96.Fc 97.Ft int 98.Fn archive_read_disk_descend "struct archive *" 99.Ft int 100.Fn archive_read_disk_can_descend "struct archive *" 101.Ft int 102.Fn archive_read_disk_current_filesystem "struct archive *" 103.Ft int 104.Fn archive_read_disk_current_filesystem_is_synthetic "struct archive *" 105.Ft int 106.Fn archive_read_disk_current_filesystem_is_remote "struct archive *" 107.Ft int 108.Fo archive_read_disk_set_matching 109.Fa "struct archive *" 110.Fa "struct archive *" 111.Fa "void (*excluded_func)(struct archive *, void *, struct archive entry *)" 112.Fa "void *" 113.Fc 114.Ft int 115.Fo archive_read_disk_set_metadata_filter_callback 116.Fa "struct archive *" 117.Fa "int (*metadata_filter_func)(struct archive *, void*, struct archive_entry *)" 118.Fa "void *" 119.Fc 120.Sh DESCRIPTION 121These functions provide an API for reading information about 122objects on disk. 123In particular, they provide an interface for populating 124.Tn struct archive_entry 125objects. 126.Bl -tag -width indent 127.It Fn archive_read_disk_new 128Allocates and initializes a 129.Tn struct archive 130object suitable for reading object information from disk. 131.It Fn archive_read_disk_open 132Opens the file or directory from the given path and prepares the 133.Tn struct archive 134to read it from disk. 135.It Fn archive_read_disk_open_w 136Opens the file or directory from the given path as a wide character string and prepares the 137.Tn struct archive 138to read it from disk. 139.It Fn archive_read_disk_set_behavior 140Configures various behavior options when reading entries from disk. 141The flags field consists of a bitwise OR of one or more of the 142following values: 143.Bl -tag -compact -width "indent" 144.It Cm ARCHIVE_READDISK_HONOR_NODUMP 145Skip files and directories with the nodump file attribute (file flag) set. 146By default, the nodump file attribute is ignored. 147.It Cm ARCHIVE_READDISK_MAC_COPYFILE 148Mac OS X specific. 149Read metadata (ACLs and extended attributes) with 150.Xr copyfile 3 . 151By default, metadata is read using 152.Xr copyfile 3 . 153.It Cm ARCHIVE_READDISK_NO_ACL 154Do not read Access Control Lists. 155By default, ACLs are read from disk. 156.It Cm ARCHIVE_READDISK_NO_FFLAGS 157Do not read file attributes (file flags). 158By default, file attributes are read from disk. 159See 160.Xr chattr 1 161.Pq Linux 162or 163.Xr chflags 1 164.Pq FreeBSD, Mac OS X 165for more information on file attributes. 166.It Cm ARCHIVE_READDISK_NO_TRAVERSE_MOUNTS 167Do not traverse mount points. 168By default, mount points are traversed. 169.It Cm ARCHIVE_READDISK_NO_XATTR 170Do not read extended file attributes (xattrs). 171By default, extended file attributes are read from disk. 172See 173.Xr xattr 7 174.Pq Linux , 175.Xr xattr 2 176.Pq Mac OS X , 177or 178.Xr getextattr 8 179.Pq FreeBSD 180for more information on extended file attributes. 181.It Cm ARCHIVE_READDISK_RESTORE_ATIME 182Restore access time of traversed files. 183By default, access time of traversed files is not restored. 184.It Cm ARCHIVE_READDISK_NO_SPARSE 185Do not read sparse file information. 186By default, sparse file information is read from disk. 187.El 188.It Xo 189.Fn archive_read_disk_set_symlink_logical , 190.Fn archive_read_disk_set_symlink_physical , 191.Fn archive_read_disk_set_symlink_hybrid 192.Xc 193This sets the mode used for handling symbolic links. 194The 195.Dq logical 196mode follows all symbolic links. 197The 198.Dq physical 199mode does not follow any symbolic links. 200The 201.Dq hybrid 202mode currently behaves identically to the 203.Dq logical 204mode. 205.It Xo 206.Fn archive_read_disk_gname , 207.Fn archive_read_disk_uname 208.Xc 209Returns a user or group name given a gid or uid value. 210By default, these always return a NULL string. 211.It Xo 212.Fn archive_read_disk_set_gname_lookup , 213.Fn archive_read_disk_set_uname_lookup 214.Xc 215These allow you to override the functions used for 216user and group name lookups. 217You may also provide a 218.Tn void * 219pointer to a private data structure and a cleanup function for 220that data. 221The cleanup function will be invoked when the 222.Tn struct archive 223object is destroyed or when new lookup functions are registered. 224.It Fn archive_read_disk_set_standard_lookup 225This convenience function installs a standard set of user 226and group name lookup functions. 227These functions use 228.Xr getpwuid 3 229and 230.Xr getgrgid 3 231to convert ids to names, defaulting to NULL if the names cannot 232be looked up. 233These functions also implement a simple memory cache to reduce 234the number of calls to 235.Xr getpwuid 3 236and 237.Xr getgrgid 3 . 238.It Fn archive_read_disk_entry_from_file 239Populates a 240.Tn struct archive_entry 241object with information about a particular file. 242The 243.Tn archive_entry 244object must have already been created with 245.Xr archive_entry_new 3 246and at least one of the source path or path fields must already be set. 247(If both are set, the source path will be used.) 248.Pp 249Information is read from disk using the path name from the 250.Tn struct archive_entry 251object. 252If a file descriptor is provided, some information will be obtained using 253that file descriptor, on platforms that support the appropriate 254system calls. 255.Pp 256If a pointer to a 257.Tn struct stat 258is provided, information from that structure will be used instead 259of reading from the disk where appropriate. 260This can provide performance benefits in scenarios where 261.Tn struct stat 262information has already been read from the disk as a side effect 263of some other operation. 264(For example, directory traversal libraries often provide this information.) 265.Pp 266Where necessary, user and group ids are converted to user and group names 267using the currently-registered lookup functions above. 268This affects the file ownership fields and ACL values in the 269.Tn struct archive_entry 270object. 271.It Fn archive_read_disk_descend 272If the current entry can be descended, this function will mark the directory as the next entry for 273.Xr archive_read_header 3 274to visit. 275.It Fn archive_read_disk_can_descend 276Returns 1 if the current entry is an unvisited directory and 0 otherwise. 277.It Fn archive_read_disk_current_filesystem 278Returns the index of the most recent filesystem entry that has been visited through archive_read_disk 279.It Fn archive_read_disk_current_filesystem_is_synthetic 280Returns 1 if the current filesystem is a virtual filesystem. Returns 0 if the current filesystem is not a virtual filesystem. Returns -1 if it is unknown. 281.It Fn archive_read_disk_current_filesystem_is_remote 282Returns 1 if the current filesystem is a remote filesystem. Returns 0 if the current filesystem is not a remote filesystem. Returns -1 if it is unknown. 283.It Fn archive_read_disk_set_matching 284Allows the caller to set 285.Tn struct archive 286*_ma to compare each entry during 287.Xr archive_read_header 3 288calls. If matched based on calls to 289.Tn archive_match_path_excluded , 290.Tn archive_match_time_excluded , 291or 292.Tn archive_match_owner_excluded , 293then the callback function specified by the _excluded_func parameter will execute. This function will recieve data provided to the fourth parameter, void *_client_data. 294.It Fn archive_read_disk_set_metadata_filter_callback 295Allows the caller to set a callback function during calls to 296.Xr archive_read_header 3 297to filter out metadata for each entry. The callback function recieves the 298.Tn struct archive 299object, void* custom filter data, and the 300.Tn struct archive_entry . 301If the callback function returns an error, ARCHIVE_RETRY will be returned and the entry will not be further processed. 302.El 303More information about the 304.Va struct archive 305object and the overall design of the library can be found in the 306.Xr libarchive 3 307overview. 308.Sh EXAMPLES 309The following illustrates basic usage of the library by 310showing how to use it to copy an item on disk into an archive. 311.Bd -literal -offset indent 312void 313file_to_archive(struct archive *a, const char *name) 314{ 315 char buff[8192]; 316 size_t bytes_read; 317 struct archive *ard; 318 struct archive_entry *entry; 319 int fd; 320 321 ard = archive_read_disk_new(); 322 archive_read_disk_set_standard_lookup(ard); 323 entry = archive_entry_new(); 324 fd = open(name, O_RDONLY); 325 if (fd < 0) 326 return; 327 archive_entry_copy_pathname(entry, name); 328 archive_read_disk_entry_from_file(ard, entry, fd, NULL); 329 archive_write_header(a, entry); 330 while ((bytes_read = read(fd, buff, sizeof(buff))) > 0) 331 archive_write_data(a, buff, bytes_read); 332 archive_write_finish_entry(a); 333 archive_read_free(ard); 334 archive_entry_free(entry); 335} 336.Ed 337.Sh RETURN VALUES 338Most functions return 339.Cm ARCHIVE_OK 340(zero) on success, or one of several negative 341error codes for errors. 342Specific error codes include: 343.Cm ARCHIVE_RETRY 344for operations that might succeed if retried, 345.Cm ARCHIVE_WARN 346for unusual conditions that do not prevent further operations, and 347.Cm ARCHIVE_FATAL 348for serious errors that make remaining operations impossible. 349.Pp 350.Fn archive_read_disk_new 351returns a pointer to a newly-allocated 352.Tn struct archive 353object or NULL if the allocation failed for any reason. 354.Pp 355.Fn archive_read_disk_gname 356and 357.Fn archive_read_disk_uname 358return 359.Tn const char * 360pointers to the textual name or NULL if the lookup failed for any reason. 361The returned pointer points to internal storage that 362may be reused on the next call to either of these functions; 363callers should copy the string if they need to continue accessing it. 364.\" 365.Sh ERRORS 366Detailed error codes and textual descriptions are available from the 367.Fn archive_errno 368and 369.Fn archive_error_string 370functions. 371.\" 372.Sh SEE ALSO 373.Xr tar 1 , 374.Xr archive_read 3 , 375.Xr archive_util 3 , 376.Xr archive_write 3 , 377.Xr archive_write_disk 3 , 378.Xr libarchive 3 379.Sh HISTORY 380The 381.Nm libarchive 382library first appeared in 383.Fx 5.3 . 384The 385.Nm archive_read_disk 386interface was added to 387.Nm libarchive 2.6 388and first appeared in 389.Fx 8.0 . 390.Sh AUTHORS 391.An -nosplit 392The 393.Nm libarchive 394library was written by 395.An Tim Kientzle Aq kientzle@FreeBSD.org . 396.Sh BUGS 397The 398.Dq standard 399user name and group name lookup functions are not the defaults because 400.Xr getgrgid 3 401and 402.Xr getpwuid 3 403are sometimes too large for particular applications. 404The current design allows the application author to use a more 405compact implementation when appropriate. 406.Pp 407The full list of metadata read from disk by 408.Fn archive_read_disk_entry_from_file 409is necessarily system-dependent. 410.Pp 411The 412.Fn archive_read_disk_entry_from_file 413function reads as much information as it can from disk. 414Some method should be provided to limit this so that clients who 415do not need ACLs, for instance, can avoid the extra work needed 416to look up such information. 417.Pp 418This API should provide a set of methods for walking a directory tree. 419That would make it a direct parallel of the 420.Xr archive_read 3 421API. 422When such methods are implemented, the 423.Dq hybrid 424symbolic link mode will make sense. 425